Thanks for your reply Vladimir. That sounds reasonable to me. I have seen DCM fMRI papers (Stephan et al. 2005 for example) in which left visual field stimuli are driving inputs to right V1 and vice versa. Would you say that modelling conditional differences in intrinsic V1 connectivity results in an equivalent model?
Thanks again!
Erin
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From: Vladimir Litvak [[log in to unmask]]
Sent: September 12, 2011 4:05 PM
To: Mazerolle, Erin
Cc: [log in to unmask]
Subject: Re: [SPM] DCM for ERP - driving inputs
Dear Erin,
You can have several different inputs by specifying several (not
necessarily different) values in the 'onset' box. However, these
inputs will be there for all conditions. One way around this is to
have one input for both V1s but allow the condition effect to modulate
the intrinsic V1 connectivity so that the responsiveness of V1 will be
much greater to contralateral than to ipsilateral stimulus. I'll ask
Karl if he thinks this an adequate solution for your situation and get
back to you if he suggests something different.
Best,
Vladimir
On Mon, Sep 12, 2011 at 7:49 PM, Mazerolle, Erin
<[log in to unmask]> wrote:
> Hello,
>
> Is it possible to specify driving inputs for DCM for ERP such that different conditions drive different regions? I have only one column for the driving inputs (despite having multiple conditions defined). Are the events from all conditions modelled as driving inputs to the specified regions?
>
> I have a task in which stimuli were presented separately to the right and left visual fields, and would like to specify left visual field stimuli as driving input to right primary visual cortex, and right visual field stimuli as driving input to left primary visual cortex.
>
> Thank you in advance for your help,
> Erin
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